When drilling, completing, and/or otherwise forming or operating on a wellbore, it is often necessary to install and/or set devices that block, seal, restrict, or isolate a portion of the wellbore. For example, sub surface safety valves (which typically include a flapper valve), are deployed to restrict the egress of lower zoned material (e.g., oil and gas); however, it is common for flapper valves to become blocked or otherwise hindered or prevented from opening, preventing production or other operations. In other situations, foreign objects (e.g., “fish”), debris, and/or other objects, can become lodged within a wellbore, especially at restrictions in a wellbore. Such items can often present difficulties in their removal due to the lack of fixation of the object in the wellbore and/or the material of the object (e.g., Inconel, Hastalloy, etc.)
Conventional methods for removing downhole obstructions include use of jars to apply a physical/mechanical force to such obstructions, pigs or similar fluid jetting systems typically used to clean a conduit (e.g., to remove paraffin or similar substances), and other similar systems that generally rely on physical/mechanical force to forcibly move an obstruction.
Prior-filed U.S. application Ser. No. 13/815,614 relates to apparatus and methods for at least partially removing an obstruction (e.g., a downhole target) from a wellbore, e.g., by penetrating the downhole target with a medium, such as molten fuel, a perforating jet or object, a blade, a corrosive medium, or other similar means for eroding, penetrating, perforating, and/or otherwise overcoming a blockage or restriction. The nozzle geometry of such a device can be varied depending on the nature of the wellbore, the medium used, and the downhole target, to facilitate overcoming the obstruction, and when desired and/or necessary, an operation may include multiple trips in which each successive trip utilizes an apparatus having a different nozzle geometry to progressively remove an obstacle and/or enlarge an opening.
A need exists for apparatus and methods for removing certain types of obstructions, such as flapper valves and other types of downhole tools, using a reduced number of trips. For example, certain types of obstructions, such as flapper valves, could be penetrated and/or otherwise affected in a manner that allows the resulting pieces to fall into the wellbore, rather than progressively enlarging a flowpath through the center of the flapper value.
Many downhole tools, including flapper valves, are conventionally formed from inconel, stainless steel, and/or other generally non-ferromagnetic materials, due primarily to the fact that ferromagnetic materials can interfere with the operation of various downhole equipment, while attracting wellbore debris (e.g., filings, cuttings, etc.) that can cause deposits, occlusions, and/or build-up within a flowpath and eventually hinder or prevent proper operation of one or more tools. Fishing and/or other methods to recover debris and/or pieces of such downhole tools are often time consuming, cumbersome, and difficult.
A need also exists for apparatus and methods usable to facilitate removal of debris and/or pieces from downhole tools, e.g., using magnetic means.
Embodiments usable within the scope of the present disclosure meet these needs.